Circuit arrangement for relay switches



June 23, 1931. K. G. JOHNSON 1,811,318

CIRCUIT ARRANGEMENT FOR RELAY SWITCHES Filed June 26, 1929 0 P Q R EZzz-L eozzge aEhwoa menial:

Patented June 23, 1931 UNITED STATES PATENT; OFFICE KARL GEORG JOHNSON, OF STOCKHOLM, SWEDEN, ASSIGNOR TO TELEFONAKTIEBO- LAGET L. M. ERICSSON, OF STOCKHOLM, SVJEIDEN, A COMPANY OF SWEDEN CIRCUIT ARRANGEMENT FOR RELAY SWITCHES Application filed June 26, 1929, Serial No. 373,907, and in Sweden April 21, 1928.

The invention relates to electric switching arrangements used especially in the automatic telephony and comprising a series of relays which serve to control automatic switching operations for establishing connections with lines or apparatus in such a manner that the connections within a group of lines or apparatus are established in a definite order of sequence. Such relay series may, by way of example, be used as a call consecution controller for executing simultaneous calls in due order of sequence or as a call distributor or searcher for bringing about an even distribution of the traffic among a number of lines or switching apparatus. The invention is substantially characterized in that the relays mutually control their circuits in such a manner that said relays, when the switching arrangement is taken into engagement are first all energized and then de-energized one after the other, the relays corresponding to calling or free lines respectively or apparatus then remaining operative until the switching operation in quest-ion is completed, whereas the other relays are immediately de-energized upon the next preceding relay being de-energized.

The drawing shows an embodiment of the invention, the relay set being assumed to work as a call distributor.

The invention will be more closely described with reference to the accompanying drawing which shows a switching arrangement or a relay switch comprising four relays A, B, C, D. Each relay is provided with two coils i. e. an operative coil AL and a holding coil HL. The circuit of the operative coil of the first relay A is adapted to be closed over a contact 1, for instance by means of a relay I, as soon as there is a call. Said circuit extends over a break contact 2 of the last relay D. The circuit of the operative coils of the relays B, C, D are adapted to be closed over normally open contacts 3, 4, 5 of the next preceding relay. The holding circuits containing the coils HL are adapted to be controlled from the corresponding lines or apparatus, for instance by means of relays E, F, G, H, which relays become operative as soon as the corresponding line or apparatus is engaged. These relays may be connected with the test contact field of selectors O, P, Q, R in such a manner as to be operated when there are calls at the lines incoming to the selectors. Thus the selectors P and Q are shown to convey calls to the call distributor and the relays F, G and I therefore must get operative The holding circuits of the first relay A extends over a normally open contact 6 on the last relay D whereas the holding circuits of the other relays extend over normally closed contacts 7 8, 9 on the next preceding relay. Further each holding circuit contains a normally open contact 10, ll, 12 and 13, and a relay K, L, M and N. These relays may be arranged to start switching operations for establishing the desired connections.

To begin with it is assumed that the switching arrangement works as a call consecution controller. Then there are calls the starting relay I becomes operative as well as one or more of the relays E, F, G, H corresponding to the calling line or lines. Should there be only one call, for instance, at the line represented by the relay F, the following switching operation sets in. The relay I closes a circuit of the operative coil AL of the relay A which is energized and closes the operative circuit of the relay B. The latter relay is energized and closes in turn the operative circuit of the relay C which closes the operative circuit of the relay D. Hereby all relays A, B, C, D are thus caused to be successively energized. When the relay D is energized, the operative circuit of the relay A is opened. As the relay E in the present example is currentless the relay A is unable to hold its armature and thus ole-energizes. The operative circuit of the relay B is then opened but instead thereof the holding circuit of the same relay is closed over the contacts 7, 11 and the contact 14 of the relay F which is now operative. The relay B accordingly remains energized and the working of the consecution controller ceases. At the same time the relay L which starts the switching operations for linln'ng up the calling line gets energized. When these switching operations are performed the relay F is de-energized. The

relay F breaks the holding circuit of the relay B. When the relay B, as a consequence, is de-energized, also the relay C is de-energized the latter in turn opening the circuit of the relay D which thus also is deenergized. If in the meantime no new call has arrived also the relay I is now de-energized. The relays A, B, C, D are thus unable to be again energized before a new call occurs, when a similar switching operation will start. I

If there are simultaneous calls on several lines it is evident that these calls will be taken care of in due order according as the different relays A, B, C, D are de-energized. When the switching arrangement is to be used as a call dist ibutor the switching operation is analogous. The relays E, F, G, H then represent the'lines over which the traffic is to be. distributed. When there are calls the relay 1 becomes operative just as before as well as one or more of the relays E, RG, H corresponding to disengaged lines. The relays A, B, C, D are energized in succession. If all lines are disengaged the switching operation will cease upon energization of the relay D, as the relay A is supplied with holding current over contacts 6 and 10. At thesaine time the relay K is energizedand a switching operation is startedby means ofwhich the calling line is connected up to the line corresponding to the relay E. WVhen this connection is performed the relay E de-energizes and if there are no more calls,

also the relay 1. Consequently the relays, A, B, C, D de-energize in succession. 1f there should be several simultaneous calls the relay I remains energized until all calls are mediated, the connections being then established successively in the manner just explained. 7

Claim. 7 I In a'circuit arrangement for telephone systems in combination a series of relays forming a relay switch adapted to be used as a call consecution controller ora call distril 'utor, working and a holding winding at each relay, the working circuit of the first relay in the series being controlled by the last relay and the working circuits of each of the following relays beingarranged to be closed by the working contacts of each of the preceding relays, a holding circuit for the first relay controlled by the last relay, and holding circuits for each of the following relays controlled by each of the preceding re lays, and a number of relays corresponding to the circuits to be served, said relays be ing adapted to control said holding circuits.

Intestimony whereof I afiix my signature.

KARL GEORG JOHNSON. 

